Sample injector for a high pressure liquid chromatograph

ABSTRACT

A SAMPLE INJECTOR FOR A HIGH PRESSURE LIQUID CHROMATOGRAPH IS DISCLOSED. THE INJECTOR INCLUDES A HOUSING COUPLED TO THE END OF THE CHROMATOGRAPHIC COLUMN. THE HOUSING INCLUDES AN INJECTOR PASSAGEWAY ALIGNED WITH THE COLUMN AND THROUGH WHICH A HYPODERMIC SYRINGE IS INSERTED FOR INJECTING SAMPLE MATERIAL INTO THE HEAD OF THE COLUMN. A BLOCKING PLATE IS PIVOTABLE INTO POSITION FOR   BLOCKING THE SAMPLE INJECTOR PASSAGEWAY, AFTER INJECTION OF THE SAMPLE, AND IS SEALED TO THE HOUSING BY MEANS OF A DEFORMABLE SEALING RING. A SCREW, WITH INTERNAL PASSAGEWAY, IS PROVIDED FOR PRESSING THE PLATE INTO SEALING ENGAGEMENT WITH THE RING AFTER INSERTION OF THE SAMPLE.

Feb. 23, 1971 v 5s EI'AL 3,564,925

SAMPLE INJECTOR FOR A HIGH PRESSURE LIQUID CHROMATOGRAPH Filed Aug. 18,1969 INVENTORS HUBERT N.DIVELBISS BILLY E. GOOSTREE AT RNEY UnitedStates Patent 3,564,925 SAMPLE INJECTOR FOR A HIGH PRESSURE LIQUIDCHROMATOGRAPH Hubert N. Divelbiss, Napa, and Billy E. Goostree, PleasantHill, Calif., assignors to Varian Associates, Palo Alto, Calif., acorporation of California Filed Aug. 18, 1969, Ser. No. 850,925 Int. Cl.G0ln 1/10 US. Cl. 73-422 Claims ABSTRACT OF THE DISCLOSURE A sampleinjector for a high pressure liquid chromatograph is disclosed. Theinjector includes a housing coupled to the end of the chromatographiccolumn. The housing includes an injector passageway aligned with thecolumn and through which a hypodermic syringe is inserted for injectingsample material into the head of the column. A blocking plate ispivotable into position for blocking the sample injector passageway,after injection of the sample, and is sealed to the housing by means ofa deformable sealing ring. A screw, with internal passageway, isprovided for pressing the plate into sealing engagement with the ringafter insertion of the sample.

Heretofore, liquid chromatographs have had sample injectors wherein arelatively thick rubber diaphragm sealed off a port in the injectorhousing. The sample was injected by pushing a hypodermic syringecontaining the sample material to be injected through the diaphragm.After insertion of the sample into the head of the chromatographiccolumn, the hypodermic syringe is withdrawn from the diaphragm. Suchdiaphragms, after perforation by the hypodermic syringe, were capable ofwithstanding only about 1,000 p.s.i.g. of liquid pressure exerted at thehead of the column before leakage was encountered through theperforations produced by insertion of hypodermic syringe. It isdesirable to provide a sample injection system for relatively highpressure liquid chromatographs which will permit the chromatograph tooperate with pressure heads on the column substantially in excess of1,000 p.s.i.g., such as from 1,000 to 20,000 p.s.i.g. withoutencountering leakage of the carrier fluid from the sample injectorsystem.

SUMMARY OF THE PRESENT INVENTION The principal object of the presentinvention is the provision of an improved sample injector for a highpressure liquid chromatograph.

One feature of the present invention is the provision in a sampleinjector housing of a passageway communicating with the head of thechromatographic column for insertion of a hypodermic syringe, suchinjector housing including a movable blocking member to be moved intoposition for blocking the sample injection passageway after injection ofthe sample, such blocking member being sealed in fluid tight relation tothe housing by means of a deformable sealing member encircling thesample introduction passageway with means for pressing the blockingmember into sealing engagement with the sealing member to provide arelatively high pressure fluid tight closure of the passageway.

Another feature of the present invention is the same as the precedingfeature wherein the blocking member includes a plate pivotably mountedwith respect to the housing such that the plate may be pivoted intoblocking position for making a seal and pivoted out of blocking positionto permit injection of the sample.

Another feature of the present invention is the same as any one or moreof the preceding features including the Patented Feb. 23, 1971 provisionof a screw threadably mating with a portion of the injector housing andbeing axially translatable with respect to the sample injectionpassageway for pressing the blocking member into sealing engagement withthe sealing member.

Another feature of the present invention is the same as the precedingfeature wherein the screw includes an axially directed passageway inline with the sample injection passageway to permit insertion of thehypodermic syringe through the screw and the passageway in the housing.

Other features and advantages of the present invention become apparentupon a perusal of the following specification taken in connection withthe accompanying drawing wherein:

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic line diagram,partly in block diagram form, depicting a relatively high pressureliquid chromatograph incorporating features of the present invention,

FIG. 2 is an enlarged sectional view of a portion of the structure ofFIG. 1 delineated by line 22,

FIG. 3 is a view of the structure of FIG. 2 taken along line 33 in thedirection of the arrows, and

FIG. 4 is a view similar to that of FIG. 3 depicting a pivotableblocking member in the unblocked position.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to FIG. 1, thereis shown a liquid chromatograph 1 incorporating features of the presentinvention. The chromatograph 1 includes a chromatographic column 2, asof 1 millimeter inside diameter and 3 to 300 feet long, packed with asuitable ion exchange resin in the form of beads having a particle sizeof approximately 1 micron. A sample injector housing structure 3 isafiixed to the head of the column 2. The injector housing 3 includes aninjector passageway 4 through which a hypodermic syringe needle 5 isinserted for injecting a sample of material 6 into the head of thecolumn 2. The injector housing 3 is more fully described below withregard to FIGS. 2-4. A liquid carrier stream is injected through thesample injector housing 3 into the head of the column 2 from a suitablesolvent pump 7 at a relatively high pressure as of 1,000 to 20,000p.s.i.g. Suitable liquid solvents, serving as the carrier liquid,include water, chloroform, ammonium formate and other liquids serving asa solvent for the sample of interest.

The liquid carrier stream carries the dissolved sample material throughthe column 2 wherein the sample constituents are separated into timedisplaced peak concentration as the eluted carrier stream exits from thecolumn to an ultraviolet detector 8. The ultraviolet detector 8 includesan ultraviolet lamp 9 which shines ultraviolet radiation through thecarrier stream to a photodetector 11. The relative absorption of theultraviolet light as absorbed by the sample constituents in the carrierstream is detected by photodetector 11 to derive an electrical outputcorresponding to the peak concentrations of the sample constituents. Thedetected output signal is fed to an amplifier 12 wherein it is amplifiedand thence fed to the input of a recorder 13 to produce a chromatogramof the sample material. The chromatogram yields both qualitative andquantitative informtion concerning the sample constituents.

Referring now to FIGS. 2-4, the sample injector 3 of the presentinvention is shown in greater detail. The sample injector housing 3includes a rectangular metallic base plate 14, as of stainless steel,having a fluid coupling fitting 15 for attachment to the end of thecolumn 2. The base plate 14 includes a sample injector bore 16 coaxiallyaligned with the axis of the column 2. A laterally directed bore 17intersects the injector bore 16 and a second fluid coupling fitting 18is affixed at the outer end of the bore 17 for connection of bore 17 tothe solvent pump 7.

A pivotably mounted blocking plate 19, as of stainless steel, is mountedto the base plate 14 by means of a pivot pin 21. Pivot plate 19 is alsoaxially slideable on the pivot pin 21. The blocking plate 19 ispivotable into a first blocking position, as indicated in FIG. 3, suchthat the plate 19 extends across and covers over the opening into bore16.

A cylindrical sealing plug structure 22 is inserted within the upper endof the injector bore 16. The sealing plug structure 22 includes alongitudinally directed bore 23 therethrough to receive a hypodermicsyringe needle slideable therethrough for injecting sample material intothe head of the column 2. The sealing plug structure is formed in twoparts 24 and 25. The lower cylindrical part 25 includes an outwardlydirected flange portion which seats against a shoulder of the bore 16 insealing engagement therewith. The lower plug member 25 is made of adeformable sealing material such as Teflon or rubber. The upper sealingmember 24 is likewise made of a deformable sealing material such asTeflon or rubber and is seated between the lower member 25 and theblocking plate 19.

The sample injector housing structure 3 includes a second rectangularplate member 27, as of stainless steel, fixedly secured to the lowerbase plate member 14 via a pair of cap screws 28. A lower surfaceportion of the second plate 27 is relieved at 29 to accommodate theblocking plate 19. Plate 27 includes a threaded bore 31 coaxiallyaligned with the sample injector bore 16. A screw 32, as of stainlesssteel, having a knurled knob portion 33 is threaded into the bore 31.The blocking plate 19 is pressed into sealing engagement with the plugstructure 22 by axial translation of the screw 32 toward the plate 19.When the plate 19 is pressed into sealing engagement with the deformableplug structure 22, a fluid tight seal is formed between the uppersurface of the cylindrical sealing plug member 24 and between the outerperiphery of the upper plug member 24 and the inside surface of the bore16. In addition, a fluid tight seal is formed between the lower plug 25and the shoulder portion of the bore 16.

The screw 32 includes a longitudinally directed bore 35 therethrough inaxial alignment with bore 23 in the plug structure 22. To inject thesample material into the column 2, the screw 32 is translated in adirection away from the blocking plate 19 thereby removing the sealingpresure from the blocking plate 19. Blocking plate 19 is then pivoted toan out of the way position as shown in FIG. 4 to permit the hypodermicsyringe to be inserted through aligned bores 35, 23 and 16 into the headof the chromatographic column 2. A sample is then injected into the headof the column 2'. The syringe is removed and the blocking plate 19 ispivoted back to the position as shown in FIG. 3 and screw 32 istightened against the plate 19 to form the seal with the plate 19 andplug structure 22. The column 2 is then pressurized by injecting solventfrom the solvent pump 7 via passageway 17 and bore 16 to the head of thecolumn 2 at pressures in the range of 1,000 to 20,000 p.s.i.g. andpreferably between the range of 1,000 to 5,000 p.s.i.g. The efficiencyof column 2 for separation of the various sample constituents isproportional to the pressure of the solvent as applied to the column 2.

A pair of mounting holes 37 are provided in the base plate 14 formounting the injector housing structure 3 4 to a suitable supportchassis or structure, not shown. In addition, an alignment pin 38 isdriven through aligned apertures in the upper and lower plates 27 andI14, respectively, to obtain proper alignment of plates -14 and 27.

Since many changes could be made in the above construction and manyapparently widely diflierent embodiments of this invention could be madewithout departing from the scope thereof, it is intended that all mattercontained in the above description or shown in the accompanying drawingsshall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. In a liquid chromatographic apparatus, means forming achromatographic column for separating sample constituents as carriedthrough said column via a liquid carrier stream under a relatively highpressure, means for introducing sample material to be analyzed into thecolumn for passage through said column, the improvement wherein, saidsample introducing means includes a housing structure having a sampleintroduction passageway therein a liquid communication with said columnand through which a sample is injected into said column, a deformablesealing member disposed encircling said sample introduction passageway,movable blocking means for movement to a first position for blockingsaid sample introduction passageway, means for applying sealing pressureto said blocking means to press said blocking means into sealingengagement with said sealing member to form a relatively high pressureliquid tight seal between said blocking means and said housing toprevent the escape of liquid carrier from said sample introductionpassage- Way when blocked and pressurized, and means for selectivelyreleasing the sealing pressure on said blocking means to permit movementof said blocking means to a second position which unblocks said sampleintroduction passageway to permit injection of the sample.

2. The apparatus of claim 1 wherein said blocking means includes a platepivotably mounted with respect to said housing.

3. The apparatus of claim 2 wherein said means for applying sealingpressure to said blocking means includes a screw threadably mating witha portion of said housing structure and being axially translatable withrespect to the axis of said sample introduction passageway for pressingsaid pivotable plate against said sealing member.

4. The apparatus of claim 3 wherein said screw is substantiallycoaxially disposed of said sample introduction passageway and isapertured in axial alignment with said passageway to permit insertion ofa sample injection tube through said aperture in said screw.

5. The apparatus of claim P1 wherein said sealing member is cylindricalhaving a centrally disposed axially directed passageway therethroughdefining a portion of said sample introduction passageway, said housngincluding a bore coaxially aligned with said sample introductionpassageway, and said cylindrical sealing member being disposed in saidbore in sealing relation with said bore at the periphery of saidcylindrical sealing member.

References Cited UNITED STATES PATENTS 3,346,486 10/1967 Winter et al73--61.1

FOREIGN PATENTS 1,215,748 11/1959 France 73-422 S. CLEMENT SWISHER,Primary Examiner

